One Cable Solution (Unicable / dCSS) LNB Explained
A One Cable Solution — Unicable (standard EN50494) or its successor dCSS/JESS (EN50607) — lets multiple satellite receivers share a single coaxial cable instead of running one cable per tuner. It works by assigning each tuner its own fixed "user band" (a slot on the cable); when a receiver wants a channel, it tells the LNB which transponder to place into its user band, and the LNB delivers it without disturbing the other tuners.
This is the go-to solution for multi-room homes and apartment buildings where running new cable is difficult. EN50494 (Unicable I) supports up to 8 user bands on one cable; EN50607 (Unicable II / dCSS / JESS) supports up to 32, making it ideal for larger installations.
The Problem It Solves
Traditionally, every satellite tuner needs its own dedicated cable back to the LNB or multiswitch because each tuner independently switches polarization (13/18V) and band (22 kHz tone). Four tuners meant four cables; eight meant eight — impractical in existing buildings with limited risers.
Unicable removes that constraint. Many tuners share one cable, so a legacy single-cable riser can serve a modern multi-tuner PVR or several rooms without rewiring. That is why one-cable solutions are standard in apartments, hotels and retrofit installations.
- Legacy wiring: one cable per tuner
- Unicable/dCSS: many tuners over a single shared cable
- Ideal for retrofits and multi-dwelling units
How User Bands Work
Each tuner is assigned a unique user band (also called a Slot or SCR — Satellite Channel Router — frequency). This is a fixed IF frequency slot reserved for that tuner on the shared cable.
When a receiver tunes a channel, it sends a special DiSEqC command up the cable telling the LNB: "take this transponder, this polarity and band, and frequency-convert it into my user band." The LNB's SCR circuitry places the requested transponder at the tuner's assigned frequency. Every tuner has its own slot, so they never collide even though they share one wire.
- User band = a fixed frequency slot per tuner
- Receiver requests a transponder → LNB converts it into that slot
- Each tuner must be configured with a unique user band number/frequency
Unicable I (EN50494) vs Unicable II / dCSS (EN50607)
The two standards differ mainly in capacity and addressing. EN50494 (Unicable I) supports up to 8 user bands per cable. EN50607 (Unicable II, also branded dCSS or JESS) supports up to 32 user bands and adds features that make configuration easier and more robust.
EN50607 is backward-compatible in the sense that it can coexist with and largely replace EN50494 in new installations. For anything beyond 8 tuners on one cable, EN50607 is required.
| Feature | Unicable I (EN50494) | Unicable II / dCSS (EN50607) |
|---|---|---|
| Max user bands per cable | 8 | 32 |
| Also known as | Unicable, SCR | dCSS, JESS |
| Best for | Small multi-room | Large multi-dwelling / hotels |
| Addressing | Basic | Enhanced |
Installation and Compatibility Notes
A one-cable installation only works if every connected receiver supports the chosen standard (Unicable I or II) and is configured with a unique user band. Two receivers sharing the same user band will fight and cause dropouts.
Plan the user-band assignment before installation, document which slot each tuner uses, and confirm receiver compatibility — most modern set-top boxes support Unicable but must have it enabled in the tuner menu. For legacy non-Unicable receivers, either use a Unicable LNB with a mix of legacy and SCR outputs, or fall back to a Quattro-plus-multiswitch architecture.
- Every receiver must support the chosen Unicable/dCSS standard and be enabled for it
- Assign a unique user band to each tuner — never duplicate slots
- Document slot assignments for future service
- Legacy receivers need a hybrid LNB or a multiswitch instead
Key Takeaways
- Unicable/dCSS lets many receivers share one coax by assigning each tuner a user band.
- EN50494 (Unicable I) supports up to 8 user bands; EN50607 (dCSS/JESS) up to 32.
- Each tuner needs a unique user band — duplicates cause conflicts.
- Ideal for retrofits, apartments and hotels with limited cabling.
- All connected receivers must support and be configured for Unicable.
Related FAQs
Unicable I is defined by EN50494 and supports up to 8 user bands. dCSS (also called Unicable II or JESS) is defined by EN50607 and supports up to 32 user bands with enhanced addressing. dCSS is the more capable successor for larger installations.
Most modern receivers do, but it must be enabled and assigned a user band in the tuner settings. Older legacy receivers may not support it, in which case you need a hybrid LNB with legacy outputs or a multiswitch.
Up to 8 tuners with Unicable I (EN50494) and up to 32 tuners with dCSS/EN50607, provided each tuner is assigned its own unique user band and all devices support the standard.